Today Betsy brought to our attention that PR3 had moved yesterday durring model restarts.  We have now moved it to bring the ALS beatnote back to 5dBm, and we have since locked the full IFO with a recylcing gain of 29.  The attached screenshot shows that the OPLev is still miscentered, so it is probably still a good idea to recenter it in the morning.  

Summary:

RIN of X arm green beam everywhere (input measured by QPD, transmission measured at corner, reflection measured by WFS) is much larger than Y arm for a broad frequency range, the descrepancy peaking at around 10Hz.

Looking at various things, the beam might be clipping somewhere between ISCTEX green Faraday and TMSX M3 (that's the HR/partial for IR/green to split the green main path and green QPD path).

This is not an ultra serious clipping, causing additional 1%-ish pk-pk RIN, but could be an issue for our initial alignment scheme. Needs more investigation.

Details:

First attachment, top panel shows various RIN when the arms are locked with reasonable alignment (ALS-TRX and TRY both more than 0.95).  Thick lines = X, thin ones =Y.

X arm RIN for input (QPD), transmission (ALS TR) and reflection (WFS DC) are all about 2 orders of magnitude larger than Y at 10Hz. The middle panel shows that the QPD signals for X arm shows similar structure, and it's mainly PIT.

On the bottom panel you see that the PIT to NSUM coherence is really high. This means that the structure is not due to some intensity noise from the laser, it's more likely that the PIT clipping is causing the RIN and increasing (or decreasing) PIT signal at the same time.

Perfect coherence between X QPDA and QPDB means that the clipping location is upstream of the QPD sled. High coherence between the QPD RIN and transmission RIN at 10Hz should mean that the clipping is upstream of TMSX M3 where transmission and QPD path are separated.

Back to the middle panel, the reflection RIN (WFS DC) is larger than input and transmission by a factor of 1.5 or so. This should mean that the clipping location cannot be upstream of the green Faraday on ISCTEX.

So the conclusion for now is that it's likely clipping between green Faraday and TMSX M3.

The noise is not stationary, it goes up and down, but it never comes down to the same level as Y arm.

The second plot shows that X arm has been like this for the past 6 months except for two brief periods.

(Note that I needed to set a factor of 0.685 calibration for X WFS DC NSUMs, as the DC value for these was about 1.45, not 1.00. I didn't have to do this to any other RINs.)

LVEA: Laser Hazard
Observation Bit: Commissioning  

07:15 Karen – Cleaning in the LVEA
08:00 Alarm on PY-199 – Notified Bubba & Kyle
08:11 Jim – Running testing on ETM-X, ITM-X, and HAM4
09:15 Kyle & Gerardo – Installing vacuum gauge on HAM1
09:25 Kyle & Gerardo – Out of the LVEA
12:09 Ken M – Going to Mid-X to recover parts
13:04 Filiberto – Working on Test Stand near Y-Arm spool
13:16 Kyle – In LVEA checking the HAM1 vacuum gauge
13:22 Kyle – Out of LVEA
13:40 Filiberto – Out of LVEA
15:17 Bubba – Going to Mid-X to receiving area
 

I have added some blinkies/flashies to the OPS_OVERVIEW medm screen. FSS: When the TPD Voltage drops below .9V a yellow alert blinker will appear under the FSS button. TCSX: A button similar to the one someone added for the Fast Shutter has been added and will turn red if the LASER should lose power. These are just for "heads-up" until something better can be arranged and implemented.

Just for referecne. If you want to decode a SWSTAT value use the following, and replace '#' with the SWSTAT value:

cdsutils sfm decode #

While Stuart and I were looking at SDF and GRD monitoring, we noticed that there were some empty filters that were requested to be on, but were not on.  I've turned them off.  Attached are the 2 screens where I found such benign filters in the half-state (ETMX L3 LOCK, and BS M2 COIL).  They are off now.  We intend to get new safe.snaps tomorrow so likely any remaining leftover empty filtering will be cleared out.

[Doug C, Jason O, Stuart A]

We are planning a B&K hammer training session on an OpLev pier during the maintenance period tomorrow. I conducted a survey of current OpLev power spectra to help identify any particular piers that we should target. The power spectra (attached below) suggest some very low resonances (3.3 Hz & 6.6 Hz) for ITMY, so we shall focus our attention there. n.b.PR3 looks to be misaligned.

Here are the trends for the past 10 days:

Seismic – Jim running tests on ETM-X, ITM-X, and HAM4 for Jeff K. 
Working on feed forward on HAM4

Suspensions – Stuart is rebuilding suspension models
Installed switchable Mid-Stage coil 
Cleaning up old/unused channels 

PSL – Realigned the RefCav to bring power up to 1.5V. Tightened loose periscope mirror mounts. These could be the source of the alignment drift.  

3IFO – Jodi and team parts hunting in the LVEA. 
They moved the IO parts top the staging building.  
The remaining three desiccant cabinets were moved to the VPW	
Danny checked optics for first contact
The Seismic team moved the last BSC-ISI into its storage container

FAC/VAC – Roughing on HAM1. 
Kyle needs to install a temporary gauge onto of HAM1
SnoValley – On site working on A/C at VPW and chiller yard
OpLev – Modifying grout forms. Hope to start grouting OpLev piers next week 

As a follow on from my alog last week (16811), I ran TFs on the PR2 while the largish IFO pointing offsets were enabled.  With offsets of P = 1816, Y = 4315, the P and Y TFs look healthy.  Phew.

With some guidance from T. Abbott, I have gotten the SUS Drift Monitor back up and functioning.  I have updated all the suspension alignments to the most recent good lock stretch of 1108702216 GPS.  After this update, a few suspensions were showing that they are misaligned from this previously good alignment. 

PR3 - Pitch, not sure why this is aligned differently now.  Trends show this changed Feb. 24 at 20:00 UTC.  I could not find an aLog specifically stating that this SUS was touched.

SR2 - Changed Pit alignment to alleviate possible rubbing.  See aLog 16831.

RM, IM, and OM alarm level are still in a state of flux.  To be continued.

No significant changes from last week.

The version of root software used on x1work has been updated to root-5.34.21, the version of gds software for x1work has been updated to gds-2.16.12.4, to match what is used in the LHO control room.

The daqd and nds software for x1dc0, x1nds1, and x1fw1 has been updated to branch 2-9, r3965.  It was fairly old, at r3626 and needed to be updated to test daqd protocol 12.1 with nds2 client software.

Since we started running feedforward on the BSC-ISI's, Jeff and Hugh noticed that the feedforward path is not controlled by Guardian. This means that if FF is engaged and the ready state is requested through Guardian, the St1 actuators will still be driving. From a safety standpoint, it looks like this probably isn't an issue. I took spectra this morning with the ITMX ISI off (FF off, too) and with FF only (no damping or isolation loops). The FF only state actually still provides some isolation above 1hz (see attached plot, dashed references are the off state, solid lines are FF only). I also turned HEPI off, then turned it back on while watching the ISI seismometers, and didn't see anything obviously terrible. The actuator signals stayed below a couple hundred counts the whole time, much like the ISI with damping only, and only the T240's got agitated while HEPI servoed to position, which is normal. It's still possible that whacking the HEPI piers could cause FF to do bad things, so...don't do that.

See JeffK's 16857 where he analyses the End Station's performance relative to the fluid pressure noise.  The attached plots compare those final performance numbers for YEND  from Sunday at 6pm pst with data taken 25 Feb at 0230utc -- after the EndY HEPI plumbing system maintenance detailed in 16899.

Bottom line--The DOFs still showing coherence on Sunday (Jeff's 16857) are all almost completely gone, there is still a bit of coherence in the HP dof in places between 10 & 100mhz.  So this maintenance would appear to be very important.  The DOFs remaining were the 'common' mode dofs.  That is, the Z and the HP modes of the HEPI--those dofs where the Actuators move in common.  All other dofs have counter moving actuators which one might expect a common noise like pump pressure to cancel out.

Now, understand, Jeff's work on the controller characterization and tuning provided most of the decoupling to the platform; this maintenance work just closed a few final loose ends.

The xml for these is /ligo/svncommon/SeiSVN/seismic/HEPI/H1/Common/2015-02-25_H1HPI_EndYStation_Coh_wISIT240s.xml

Kyle, Gerardo 

Added remaining bolts to HAM1 West door and finished torquing -> Soft-closed GV5 and GV7 (GV5 hard-closed on its own at only 20 psi) -> Pumped HAM1 with scroll pump via vent/purge valve (as such, atmospheric pressure remains on air-side of closed vent/purge valve) -> Opened GV5 and GV7 

Richard M. is investigating getting signal cables to HAM1 gauges 

(Kiwamu, Dave, Jim, Jeff, Daniel)

The LSC and OMC models have been re-partitioned, so that DARM and CARM (to the ifo) are processed in the OMC.

• New input and output matrices have been added. We are upgrading the guardian to use Jamie's new matrices which uses channel names rather than numeric indices as rows and columns. This should make us more robust against changes in the future.
• All DARM signals are now processed in the OMC model, ie., ALS_DIFF, ASAIR_A_RF45 and DCPDs. This should eliminate 62µs of delay in the DARM path.
• A new MCL feedback path was added to the LSC to take over what has previously been done by the CARM module (feedback to MC2).
• We fixed the long standing naming conflict in the IMC servo, the filter module is now called IMC-MCL.
• All references to OAF have been replaced by CAL (mainly in names of IPC modules).
• The IMC-F signal is additionally routed to the OMC model and out as the common tidal signal to the end stations. The tidal script is no longer required.
• New medm screens are available.
• And committed to svn.

The current processing times are:

Only the OMC sends data to the ETMX/Y, and only ISCEX/Y send data back to the LSC. With no more than 13µs processing time one might expect that there is plenty of time to send the DARM signal to the ETMs without an IPC errors. But no! We still have one every couple of seconds. This is down from a ~10Hz error rate. Strangely, the ALS, which picks up the common tidal signal and is located after the SUS in the fiber loop, does not see any errors. We now suspect a problem at the receiving end. More investigations ongoing.